Just read each line, remove the line terminator (chomp) then split name and value and add value to the appropriate hash element.

$ perl -Mstrict -Mwarnings -MData::Dumper -E '
open my $dataFH, q{<}, \ <<EOF or die $!;
john, 100
barry, 300
john, 200
mary, 150
barry, 200
EOF

my %names;
while ( <$dataFH> )
{
    chomp;
    my( $name, $value ) = split m{\s*,\s*};
    $names{ $name } += $value;
}

print Data::Dumper->Dumpxs( [ \ %names ], [ qw{ *names } ] );'
%names = (
           'john' => 300,
           'barry' => 500,
           'mary' => 150
         );
$
[download]

I hope this is helpful but ask further if you need more explanation.

Hi johngg,

I see you recognized that the OP got tricked by using %seen and tracking the names he'd seen, when he wanted to track the numbers

You chose %names but I called it %sum

 $names{ $name } += 4; reads like "names of $name is increasing",
"names of bob is increasing" ...
but you're not increasing the names :)
you're not tracking the name,
you're tracking some attribute of name,
you're increasing the %sum, the %cash, %accountBalance,

See Re: What are the most basic, generic aspects of programming?, Re: Perl Best Practices for naming variables, About the use of the plural form for the name of variables, About the use of the plural form for the name of variables, Perl Best Practices for naming variables

Thanks johngg

Hi, johngg beat me to it, but, I would have said, you could just rename %uniq to %sum and do "increasing/decreasing" inside the loop

You got tricked by your choice of variable name, see Re^4: adding values of element, so I just wanted to emphasize that for you